用递等式计算.①987+104×65-1747② 37 63 ÷7+ 1 7 × 26 63 ③(

2025-05-17 17:13:46
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回答1:

①987+104×65-1747,
=(1000-13)+(100+4)×65-1747,
=1000-13+6500+260-1747,
=1000-13+6500+200+60-1700-47,
=(1000+6500+200-1700)+(60-13-47),
=6000+0,
=6000;

37
63
÷7+
1
7
×
26
63

=
37
63
×
1
7
+
1
7
×
26
63

=(
37
63
+
26
63
)×
1
7

=1×
1
7

=
1
7


③(
7
9
+
4
21
-
3
7
)×6.3,
=
7
9
×6.3+
4
21
×6.3-
3
7
×6.3,
=4.9+1.2-2.7,
=3.4;

④15÷[(
5
7
-
1
2
)÷
3
28
]-0.5,
=15÷[
3
14
×
28
3
]-0.5,
=15÷2-0.5,
=7.5-0.5,
=7.